Cacao, the plant from which chocolate is made, was domesticated around 1,500 years earlier than previously thought, and in South America rather than Central America, reports a paper published online this week in Nature Ecology & Evolution.
Theobroma cacao was a culturally important crop in pre-Columbian Mesoamerica. Cacao beans were used both as currency and to make the chocolate drinks consumed during feasts and rituals. Archaeological evidence of the crop’s use, dating back to 3,900 years ago, has helped to cement the idea that T. cacao was domesticated in Central America. However, genetic evidence shows that the highest diversity of T. cacao and related species are found in equatorial South America, where cacao is important to contemporary indigenous groups, hinting that this may actually be where the domestic crop originated.
Michael Blake and colleagues studied ceramic artefacts from Santa Ana-La Florida, the earliest known site of Mayo-Chinchipe culture, which was occupied from at least 5,450 years ago. The authors found three lines of evidence to show that the Mayo-Chinchipe culture used cacao between 5,300 and 2,100 years ago: the presence of starch grains specific to Theobroma on the interior of potsherds; residues of theobromine, a bitter alkaloid found in T. cacao but not its wild relatives; and fragments of ancient DNA with sequences unique to T. cacao.
These findings suggest that the Mayo-Chinchipe people domesticated T. cacao at least 1,500 years before the crop was used in Central America. As some of the artefacts from Santa Ana-La Florida have links to the Pacific coast, the authors propose that trade of goods, including culturally important plants, could have started cacao's voyage north.